[Webkit-unassigned] [Bug 241920] New: canPlayType and video codec filtering fail for VP8 on Mac with VP8 but not VP9 hardware codecs

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Thu Jun 23 09:46:59 PDT 2022


            Bug ID: 241920
           Summary: canPlayType and video codec filtering fail for VP8 on
                    Mac with VP8 but not VP9 hardware codecs
           Product: WebKit
           Version: Safari 15
          Hardware: Mac (Intel)
                OS: macOS 12
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Media
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: bvibber at wikimedia.org

Created attachment 460445

  --> https://bugs.webkit.org/attachment.cgi?id=460445&action=review

Screenshot of the linked/described examples: the top with full codec description fails, while the bottom works. If you try this on a newer Mac with hardware VP9 it will load both videos.

On an early-2015 Retina MacBook Pro 13" running macOS 12.4 and both current Safari and Technology Preview, HTMLMediaElement.prototype.canPlayType and the filtering of <video> <source>s based on codecs in the type attribute indicate that both VP9 and VP8 are not supported, however:

1) if you don't specify a codec, and just specify 'video/webm', it does play

2) the CPU is an Intel Core i7-5557U, which has Intel Iris Graphics 6100, which includes a hardware VP8 decoder, so it *should* work unless macOS doesn't support it -- in which case 1) would not happen

Example URL: https://brionv.com/misc/hls-test/vp8-webm.html

Key bits being this fails:

        <video controls width=640 height=360>
            <source type="video/webm; codecs="vp8, vorbis"" src=polyphon-vp8-vorbis.webm>

but this works:

        <p>WebM VP8/Vorbis marked as <code>video/webm</code>:</p>
        <video controls width=640 height=360>
            <source type="video/webm" src=polyphon-vp8-vorbis.webm>

on the affected device.

I've been trying to make a local WebKit build to see if I can patch it, however no local build I produce actually seems to support WebM video -- is there a special parameter I need to be passing to the build script? As far as I can tell the ENABLE_VP9, ENABLE_VORBIS, etc are switched on thanks to building for Mac with a recent SDK? Is there anything else that needs to be done?


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